Teses / dissertações sobre o tema "Alkanes"
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Khalil, Enam A. S. A. "A thermodynamic study of binary and ternary mixtures of some alkanes and alkanols". Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328889.
Texto completo da fonteLøften, Thomas. "Catalytic isomerization of light alkanes". Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1909.
Texto completo da fonteIn recent years the levels of sulfur and benzene in the gasoline pool have been reduced, and in the future there may also be new regulations on vapor pressure and the level of aromatics and olefins as well. The limitations on vapor pressure and aromatics will lead to reduced use of C4 and reformate respectively. The branched isomers of C5 and C6 alkanes have high octane numbers compared to the straight chain isomers, and are consequently valuable additives to the gasoline pool. To maintain the octane rating, it is predicted that an increased share of isomerate will be added to the gasoline pool.
Today there is a well established isomerization technology with platinum on chlorided alumina as the commercial catalyst for both isomerization of n-butane and of the C5/C6 fraction. This catalyst is very sensitive to catalyst poisons like water and sulfur, and strict feed pretreatment is required. Zeolites promoted by platinum are alternatives as isomerization catalysts, and has replaced Pt/alumina catalysts to some extent. The Pt/zeolite catalyst is more resistant to water and sulfur compounds in the feed, but it is less active than platinum on chlorided alumina. It does therefore require a higher reaction temperature, which is unfortunate since the formation of the branched isomers of the alkanes is thermodynamically favored by a low temperature.
Because of the limitations of the two types of isomerization catalysts, there is a search for a new catalyst that is resistant to sulfur and water in the feed and is highly active so it can be operated at low temperature. A new type of catalyst that seems to be promising in that respect is sulfated zirconia.
The first part of this study focuses on a series of iron and manganese promoted SZ catalysts. The catalysts were characterized by various techniques such as XRD, TGA, N2 adsorption and IR spectroscopy of adsorbed pyridine. The catalytic activity in n-butane isomerization at 250°C and atmospheric pressure was compared to the physical and chemical properties of the samples. No promoting effect of iron and manganese was found when n-butane was diluted in nitrogen. When nitrogen was replaced by hydrogen as the diluting gas the activity of the unpromoted SZ sample was dramatically lowered, while the activity of the promoted catalyst was not significantly changed.
If we only consider the promoted samples, the catalytic activity increases with increasing iron/manganese ratio. We also observe that the activity of the samples is clearly correlated with the number of strong Brønsted acid sites. The total number of strong acid sites (i.e. the sum of Brønsted and Lewis sites) does not change significantly when the promoter content is changing, hence no correlation between catalytic activity and the total number of acid sites is found. This underlines the importance of discrimination between Lewis and Brønsted acidity when characterizing the acidity of the samples.
The second part of this study is focused on a series of noble metal promoted sulfated zirconia. Their catalytic activity in n-hexane isomerization at high pressures was compared to a commercial Pt/zeolite catalyst. Among the noble metal promoted samples the catalyst promoted with platinum was the most active. The samples promoted with rhodium, ruthenium and iridium showed equal activity.
Common for all the noble metal promoted catalysts is the large increase in activity when catalysts are reduced with hydrogen compared to when they are pretreated in helium. The increase in activity is most likely connected to the reduction of the metal oxides of the promoters to ensure that the promoters are in the metallic state. Reduction at too high temperatures does however give lower activity. This is probably due to the reduction of surface sulfate groups leading to a loss in acid sites.
The commercial sample was considerably less active than the sample of platinum promoted sulfated zirconia. The commercial catalyst was however more stable than the PtSZ catalyst. All the sulfated zirconia catalysts deactivated, but the initial activity could be regenerated by reoxidation at 450°C followed by reduction at 300°C. The promotion with noble metals appears to inhibit coke formation on the catalyst. But, the main cause of deactivation of the platinum promoted sample is most likely the reduction of sulfate species leading to a loss of acid sites.
The kinetic study of the catalysts indicates that the n-hexane isomerization proceeds via a classical bifunctional mechanism where the role of the promoting metal is to produce alkenes, which are subsequently protonated on the acid sites. The reaction orders of hydrogen, n-hexane and total pressure are all in accordance with this mechanism. The activation energies of the catalysts are within the typical range of bifunctional catalysts.
All catalysts, except the unpromoted SZ sample, showed close to 100% selectivity to branched hexane isomers and a similar distribution of these isomers. The isomer distribution being the same for both the noble metal promoted catalyst and the Pt/zeolite is another indication that the isomerization proceeds via the bifunctional mechanism over the promoted samples. The different selectivity of the unpromoted SZ catalyst indicates that the isomerization proceeds via a different pathway over this catalyst; this is probably a pure acidic mechanism
The acidity characterization can not explain the differences in isomerization activity. It is however likely that the activity of the promoting metals in the dehydrogenation of alkanes is important since the classical bifunctional mechanism is prevailing.
Pongtavornpinyo, Ruti. "Indium Carbenes Alkenes and Alkanes". Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508494.
Texto completo da fonteMarozzelli, Filippo. "Alkanes activation over oxide catalysts". Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/60089/.
Texto completo da fonteZHENG, TAO. "MOLECULAR SIMULATION OF DIFFUSION AND SORPTION OF ALKANES AND ALKANE MIXTURES IN POLY[1-(TRIMETHYLSILYL)-1-PROPYNE]". University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973701057.
Texto completo da fonteXu, Xiangrong. "Uranyl ion sensitised photooxidation of alkanes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq27436.pdf.
Texto completo da fonteGomes, Ana Catarina Costa. "Photocatalysis : Carbonylation of arenas and alkanes". Thesis, University of York, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516370.
Texto completo da fonteSmith, Paul Andrew. "Simulation studies of alkanes and surfactants". Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314225.
Texto completo da fonteShiimi, Annatolia. "Modeling Diiron enzymes for alkanes activation". Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/10669.
Texto completo da fonteIncludes bibliographical references.
The synthesis and characterization of a series of ruthenium 'sawhorse' complexes of the type [RU2(IJ-02CRh(CO)4(Lh]' has been successfully carried out. The complexes have been characterized by IR, 1H and 13C NMR spectroscopy, elemental analysis as well as by mass spectrometry.
Correia, Leslie Daniel Camara. "Oxygen transfer in hydrocarbon-aqueous dispersions and its applicability to alkane-based bioprocesses". Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/999.
Texto completo da fontePerry, Jason Kendrick Goddard William A. "Alkane activation by first, second, and third row transition metal ions organometallic chemistry in the gas plate /". Diss., Pasadena, Calif. : California Institute of Technology, 1994. http://resolver.caltech.edu/CaltechTHESIS:11122009-152204878.
Texto completo da fonteAdvisor names found in the Acknowledgements pages of the thesis. Title from home page. Viewed 01/14/2010. Includes bibliographical references.
Ramakrishnan, Ayyappan. "Visible light induced catalytic sulfoxidation of alkanes". [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981136915.
Texto completo da fontePutra, Edy Giri Rachman. "Solution crystallization of long chain n-alkanes". Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401188.
Texto completo da fonteGallagher, P. "The reductive decomposition of bis-diazo-alkanes". Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381343.
Texto completo da fonteSu, Yee San 1977. "The heterogeneous partial oxidation of light alkanes". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28306.
Texto completo da fonteIncludes bibliographical references.
(cont.) With this approach, an upper bound on the yield for OCM was computed. Results showed that even with optimal surface chemistry, strict limits existed on the attainable yield. Surface energetics necessary for superior OCM performance were identified and the origins of these requirements elucidated. The resulting upper bound on OCM yield under conventional, packed-bed, continuous-feed operation was found to be 28%. The catalytic properties of LiCl/sulfated ZrO₂-based catalysts were explored for ODHE. LiCl was shown to strongly interact with the acid sites on sulfated ZrO₂ (SZ), influencing its catalytic behavior. Two approaches were taken to modify the nature/strength of the LiCl-support interaction. Firstly, LiCl/Nd₂O₃-impregnated MoO/ZrO₂ and WOx/ZrO₂ were examined. Unlike SZ, these supports allowed for the tailoring of MoO[sub]x and WO[sub]x surface densities, which in turn drastically altered their ODHE performance. The poor stability of these supports, however, rendered them inferior to SZ. Secondly, the effects of dopant incorporation on the catalytic behavior of LiCI/MO,/SZ were studied. Si-doped ZrO₂-based catalysts synthesized via the sol-gel method were found to exhibit superior activity, selectivity and stability for ODHE. Sulfate decomposition experiments related the ODHE activity of these materials to the influence of the Si dopant on the sulfate binding strength. The sol-gel synthesis conditions were optimized with respect to sol pH, water:alkoxide ratio and silicon precursor, achieving improved catalyst homogeneity and enhanced ODHE performance ...
Within the petrochemical industry, a sizeable economic incentive exists for the upgrading of low-value, light alkanes. For instance, the dehydrogenation of ethane to ethene is of considerable interest due to ethene's use as a polymeric and chemical precursor. Partial oxidation provides an attractive alternative to standard pyrolysis methods for alkane-to-alkene conversion. Unlike pyrolysis, partial oxidative routes are largely unaffected by coke formation and have the added benefit of exothermicity. With the inclusion of oxygen as a reactant, however, numerous additional reaction pathways result. Among these, the presence of parallel and consecutive reaction channels to CO[sub]x products is of major concern. For this reason, previous efforts to create selective partial oxidation catalysts with high activity have typically fallen below economic feasibility requirements. This thesis focuses on the following alkane-to-alkene transformation reactions: Oxidative Coupling of Methane (OCM): 2CH₄ + O₂ <--> C₂H₄ + 2 H₂O Oxidative Dehydrogenation of Ethane (ODHE): C₂H₆ + 1/2 O₂ <--> C₂H₄ + H₂O Oxidative Dehydrogenation of Propane (ODHP): C₃H₈ + 1/2 O₂ <--> C₃H₆ + H₂O. Regarding OCM, an approach was presented for determining an upper bound on the yield of a catalytic process, which allowed for variations in the catalytic chemistry. Scaling and thermodynamic arguments were used to set parameters of an elementary step surface mechanism at values resulting in optimal yields, subjected only to physical constraints. Remaining unknowns were treated as independent variables and varied over a broad range. The result was a set of thermodynamically consistent mechanisms with optimal kinetics that could be incorporated into reactor-transport models.
by Yee San Su.
Ph.D.
Grant, C. R. "Evaluation of the bio-oxidation of alkanes". Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1367613/.
Texto completo da fonteWaldstein, Nathaniel A. "Analysis of pump oil and alkanes evaporation". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002786.
Texto completo da fonteCriswell, Leah. "Neutron diffraction and quasielastic neutron scattering studies of films of N-alkanes and a branched alkane absorbed on graphite". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6010.
Texto completo da fonteThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 11, 2008) Includes bibliographical references.
Peter, Sebastian. "Oxyfunctionalization of alkanes, alkenes and alkynes by unspecific peroxygenase (EC 1.11.2.1)". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-113321.
Texto completo da fonteDie Gruppe der Unspezifischen Peroxygenasen (EC 1.11.2.1) umfasst extrazelluläre Häm-Thiolat-Enzyme, die mittels H2O2 als Cosubstrat die selektive Monooxygenierung unterschiedlicher organischer Verbindungen katalysieren. In der vorliegenden Arbeit konnte gezeigt werden, dass die von Agrocybe aegerita sekretierte Peroxygenase (AaeUPO) verschiedene lineare (z. B. n-Hexan), verzweigte (z. B. 2,3-Dimethylbutan) und zyklische Alkane (z. B. Cyclohexan) hydroxyliert. Die Größe der von der AaeUPO umgesetzten Substrate reichte vom gasförmigen Propan (C3) bis hin zu n-Hexadekan (C16). Die Alkane wurden bevorzugt am zweiten und dritten Kohlenstoffatom (C2 und C3) hydroxyliert; eine Hydroxylierung am terminalen Kohlenstoff konnte nur vereinzelt und in geringem Umfang beobachtet werden. Die Überoxidationen der primär gebildeten, sekundären Alkohole führte außerdem zur Entstehung der entsprechenden Ketonderivate. Darüber hinaus wurde eine Vielzahl linearer terminaler (z. B. 1-Hepten), verzweigter (z. B. 2-Methyl-2-Buten) und zyklischer Alkene (z. B. Cyclopenten) sowie linearer und zyklischer Diene (1,3-Butadien, 1,4-Cyclohexadien) durch die AaeUPO epoxidiert. Die Umsetzung terminaler Alkine (z. B. 1-Octin) führte zur Entstehung der jeweiligen 1-Alkin-3-ole. Manche dieser Reaktionen verliefen ausgeprägt regioselektiv und, im Falle der linearen Alkane sowie der linearen terminalen Alkene und Alkine, mit mittlerer bis hoher Stereoselektivität. So ergab beispielsweise die Umsetzung von n-Octan einen Enantiomerenüberschuss größer 99% für (R)-3-Octanol; die Epoxidierung von 1-Hepten lieferte einen Enatiomeerenüberschuss (ee) von bis zu 72% für das (S)-Enantiomer. Die katalytischen Effizienzen, die für die Hydroxylierung bzw. Epoxidierung der Modellverbindungen Cyclohexan und 2-Methyl-2-Buten ermittelt wurden, betragen 2.0 × 103 M-1 s-1 und 2.5 × 105 M−1 s−1. Der ausgeprägte Deuterium-Isotopen-Effekt, der im Zuge der Umsetzung von semideuteriertem n-Hexan beobachtet wurde sowie die Ergebnisse des Radical-Clock-Experiments mit Norcarane als Substrat bestätigten, dass die Hydroxylierung von Alkanen über Wasserstoffabstraktion, die Bildung eines Substratradikals und anschließende direkte Sauerstoffrückbindung verläuft. Die Stopped-Flow-Experimente belegen zudem das Auftreten eines Porphyrin-Kationradikal-Intermediates (Compound I; AaeUPO-I) im katalytischen Zyklus der AaeUPO (vergleichbar mit dem reaktiven Intermediat der P450-Monooxygenasen)
Grootboom, Natasha Denise. "Alkane oxidation using metallophthalocyanine as homogeneous catalysts". Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1007794.
Texto completo da fonteStevenson, Julie-Anne. "Selective oxidation of simple alkanes by cytochrome P450cam". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302491.
Texto completo da fonteEl, Nikheli A. H. D. "Phase equilibria in mixtures containing alkanes and alcohols". Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/10419.
Texto completo da fonteHall, Christopher. "The coordination of alkanes to transition metal fragments". Thesis, University of York, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.331939.
Texto completo da fonteBourdin, Vincent, Stefano Brandani, Alfeno Gunadi, Hervé Jobic, Cordula Krause, Jörg Kärger e Wolfgang Schmidt. "Diffusion of n-alkanes in MFI-type zeolites". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196416.
Texto completo da fonteMoses, Alvira. "Synthesis of surface active alkanes for cellulose modification". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/4874.
Texto completo da fonteThesis (MSc (Polymer Science))--University of Stellenbosch, 2006.
ENGLISH ABSTRACT: The properties and interactions of cellulose surfaces are of a great technical interest during papermaking and recycling. Sizing, the modification of fiber surfaces, e.g. with the purpose to reduce water penetration into the paper structure, plays an important role in obtaining paper with good printability and water resistance. Water resistance is the key end-property of paper being investigated in this study. Firstly a comparison was made between the degree of surface modification of cellulose by means of anionic, nonionic and reactive surfactants. The amount of surfactant adsorbed by the paperboard was determined and the paper surface evaluated via scanning electron microscopy (SEM). The sizing efficiency of the three industrial surfactants was evaluated in order to establish the surfactant structure best suited for sizing recycled paperboard. This was done via the Cobb test, an industrial method to measure water uptake by paper, and contact angle measurements. The reactive surfactant was found to have the best sizing efficiency and focus shifted to synthesizing selected copolymer surfactants via free radical copolymerization. Two copolymers were synthesized, with maleic anhydride as the polar part in both. Butyl methacrylate and lauryl methacrylate were selected as the hydrophobic parts in the respective copolymer systems. The unavailability of reactivity ratios for the respective copolymer systems led to the use of in situ proton nuclear magnetic resonance spectroscopy CH NMR) for the determination of the co-monomer incorporation in both copolymer systems. Quantitative 13C NMR spectroscopy was also employed in order to establish the co-monomer content of the isolated copolymers obtained during bench-scale (laboratory) experiments. Lastly, a comparison of the degree of surface modification of cellulose was made between that which was achieved with the industrial reactive surfactant and that with the two synthesized polymeric reactive surfactants. The two synthesized polymeric surfactants were found to have a better sizing efficiency than the industrial reactive surfactant, and the maleic anhydride-lauryl methacrylate copolymer system gave the best results.
AFRIKAANSE OPSOMMING: Die eienskappe en interaksies van sellulose-oppervlaktes is van groot tegniese belang gedurende die vervaardiging en hergebruik van papier. Oppervlakte behandeling, die modifikasie van vesel-oppervlaktes bv. met die doel om water indringing in die papierstruktuur te verminder, speel 'n belangrike rol in die daarstel van papier met goeie drukkwaliteit en waterweerstand. Waterweerstand is die sleuteleienskap van papier wat in hierdie werkstuk ondersoek word. Eerstens is daar 'n vergelyking getref tussen die verandering van sellulose-oppervlaktes deur middel van anioniese, nie-ioniese en reaktiewe sepe. Die hoeveelheid seep geabsorbeer deur die papierbord is bepaal en die papier-oppervlak ondersoek deur middel van skandeer-elektronmikroskopie (SEM). Die behandelingsdoeltreffendheid van die drie industriele sepe is ondersoek om vas te stel watter seep die beste struktuur het om hergebruikte papierbord effektief te behandel. Dit is gedoen deur middel van die Cobbtoets, 'n industriele metode om wateropname van papier te meet, asook kontakhoekmetings. Daar is gevind dat die reaktiewe seep die beste behandelingsdoeltreffendheid het en daar is vervolgens gekonsentreer op die bereiding van geselekteerde reaktiewe kopolimeersepe deur middel van vryeradikaalkopolimerisasie. Twee kopolimere is berei, met maleienanhidried as die polere gedeeite van albei. Butielmetakrilaat en laurielmetakrilaat is gekies vir die nie-polere gedeeltes van die onderskeie kopolimeersisteme. Die onbeskikbaarheid van reaktiwiteitsverhoudings vir die onderskeie kopolimeersisteme het gelei tot die gebruik van in situ proton kern magnetiese resonansie spektroskopie eH KMR) vir die bepaling van die ko-monomeer insluiting in beide kopolimeersisteme. Kwantitatiewe koolstofdertienkemmagnetieseresonansie spektroskopie (13C KMR) is ook gebruik om die ko-monomeerinhoud van die geisoleerde kopolimere, verkry tydens laboratoriumeksperimente, te bepaal. Laastens is 'n vergelyking getref tussen die graad van modifikasie van selluloseoppervlaktes deur middel van die industriele reaktiewe seep in vergelyking met die twee bereide polimeriese reaktiewe sepe. Daar is gevind dat die twee gesintetiseerde polimeriese sepe beter behandelingsdoeltreffendheid as die industriele reaktiewe seep het, met die maleienanhidried-laurielmetakrilaat-kopolimeersisteem wat die beste resultaat lewer.
Schwarz, Cara Elsbeth. "The phase equilibrium of alkanes and supercritical fluids". Thesis, Stellenbosch : University of Stellenbosch, 2001. http://hdl.handle.net/10019.1/2532.
Texto completo da fonteCurrent methods for wax fractionation result in products with large polydispersity, and due to the high temperatures required, thermal degradation of the wax is often incurred. The need for an alternative process thus exists. The purpose of this project is to investigate the technical viability of supercritical fluid processing as an alternative wax fractionation technology. The main aims of this project are to select a suitable supercritical solvent, to conduct binary phase equilibrium experiments, to determine if the process is technically viable and to investigate the ability of various equations of state to correlate the phase equilibrium data. Based on limited data from the literature, propane and a propane rich LPG (Liquefied Petroleum Gas) were selected as suitable solvents. Literature data for propane and high molecular weight alkanes is scares and incomplete, thus necessitating experimental measurements. A phase equilibrium cell was designed, constructed and commissioned. The cell was designed for pressures up to 500 bar and temperatures to 200 oC, and with the aid of an endoscope, the phase transitions were detected visually. The measurements correspond well to literature values from reliable research groups. Phase equilibrium data sets for propane with nC32, nC36, nC38, nC40, nC44, nC46, nC54 and nC60 as well as LP Gas with nC36 were measured. At temperatures just above the melting point of the alkanes, the phase transition pressures can be considered to be moderate, which will positively impact the economics of the process. The phase transition pressure increases with increasing carbon number, the relationship being found to be linear when the pressure is plotted as a function of carbon number at constant mass fractions and temperature. The increase in phase transition pressure with increasing carbon number indicates that the solvent will be able to selectively fractionate the wax. At higher temperatures the gradient of the line is larger and may thus lead to improved selectivity. The higher temperatures will also lead to better mass transfer. The linear relationship indicates that limited extrapolation to higher carbon numbers may be possible. However, this needs to be verified experimentally. The inability to measure the critical point and vapour pressure curves of the higher molecular weight normal alkanes, as well as the inability of cubic equations of state to predict liquid volumes and to capture the chain specific effects such as internal rotations, results in cubic equations of state requiring large interaction parameters to fit the data. The alternative, statistical mechanical equations of state, have difficulty in predicting the critical point of the solvent correctly and thus overpredicts the mixture critical point, yet require smaller interaction parameters to fit the data. Further work is required to improve the predictability of these non-cubic equations of state. This project has proven that wax fractionation by supercritical extraction with propane is technically feasible.
Du, Xian. "Catalysis for CO2 activation reactions with light alkanes". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:924c17f7-5b71-4e70-b304-e0686d0413ea.
Texto completo da fonteWickramarachchi, P. A. S. R. "Vibrational spectroscopy of linear and branched long alkanes". Thesis, Sheffield Hallam University, 2006. http://shura.shu.ac.uk/20531/.
Texto completo da fonteGalassi, Giulio Roberto. "Monte Carlo simulations of diatomics, polymers and alkanes". Thesis, University of Southampton, 1993. https://eprints.soton.ac.uk/421719/.
Texto completo da fonteXu, Wenjian. "Fluorination Effect on the Conformational Properties of Alkanes". Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3103/.
Texto completo da fonteAbudawood, Raed Hasan. "Hydroisomerization of alkanes over metal-loaded zeolite catalysts". Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/hydroisomerization-of-alkanes-over-metalloaded-zeolite-catalysts(4511d50c-ff42-49e6-9a8a-d7ad88576bb1).html.
Texto completo da fonteMaeda, Nobuo, e nobuo@engineering ucsb edu. "Phase Transitions of Long-Chain N-Alkanes at Interfaces". The Australian National University. Research School of Physical Sciences and Engineering, 2001. http://thesis.anu.edu.au./public/adt-ANU20011203.151921.
Texto completo da fontePaunovic, Irena. "Solid-liquid phase behavior of mixtures of n-alkanes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/MQ48067.pdf.
Texto completo da fonteDe, Silva D. S. M. "Crystallization and molecular conformation of long chain N alkanes". Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246907.
Texto completo da fonteHobbs, Paul Michael. "Computational sorption studies of alkanes and alkenes in zeolites". Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320085.
Texto completo da fonteHuguet, Edouard. "Terminal oxidation of long linear alkanes in liquid phase". Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54952/.
Texto completo da fonteLeroy, Frederic H. R., Hervé Jobic, Bernard Rousseau e Alain H. Fuchs. "Self-diffusion of n-alkanes in MFI-type zeolites". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194594.
Texto completo da fonteGorce, Jean-Philippe. "Crystallisation and chain conformation of long chain n-alkanes". Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19705/.
Texto completo da fonteOrdakowski, Amy L. "Alkanes as Internal Markers to Estimate Digestibility in Horses". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/46511.
Texto completo da fonteMaster of Science
Maeda, Nobuo. "Phase transitions of long-chain n-alkanes at interfaces". View thesis entry in Australian Digital Theses Program, 2001. http://thesis.anu.edu.au/public/adt-ANU20011203.151921/index.html.
Texto completo da fonteStothard, Nigel David. "The oxidation of trans-2-butene and propene between 400 and 520 degree C". Thesis, University of Hull, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333710.
Texto completo da fonteSmart, Sharon Patricia. "Structural and dynamic properties of alpha, omega-dibromoalkanes and other guest molecules in their urea inclusion compounds". Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/14930.
Texto completo da fonteSorigue, Damien. "Biosynthèse d'hydrocarbures dérivés des acides gras chez les microalgues". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4084.
Texto completo da fonteAlkanes and alkenes are important in industry. Alkanes and alkenes are synthesized from fatty acids by a variety of organisms, such as plants and insects. However, the presence in microalgae of enzymes converting fatty acids into hydrocarbons has been poorly studied. The aim of this work was to investigate the presence of alkanes and alkenes in various microalgae models, and try to identify the enzymes responsible for the synthesis of these compounds.We have first demonstrated the presence of linear hydrocarbons C15-C17 in microalgae Chlorella and Chlamydomonas. Then we have shown that the main hydrocarbon formed in Chlorella and Chlamydomonas was derived from cis-vaccenic acid and was synthesized only in the presence of light. Absence of homologues of genes coding for known alkane/alkene biosynthetic enzymes in the genome of Chlorella and Chlamydomonas indicate the presence of an unknown pathway. Enzymatic purification and proteomic analysis allowed to identify a candidate enzyme which, expressed in E. coli lead to the formation of hydrocarbons with variable chain lengths, thus demonstrating that it was really an synthase alkane. Characterization showed that the enzyme was a photoenzyme, which used blue light to catalyse the decarboxylation of fatty acid to an alka(e)ne. The three-dimensional structure of this enzyme revealed a hydrophobic tunnel containing the fatty acid and the FAD cofactor
Fisk, Aaron T. "Dietary accumulation, sediment bioavailability and toxicity of polychlorinated n-alkanes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0028/NQ31980.pdf.
Texto completo da fonteArnold, Thomas. "The adsorption of alkanes from their liquids and binary mixtures". Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249654.
Texto completo da fonteThompson, Richard Lewis. "Surfactant properties of semifluorinated alkanes in hydrocarbon and fluorocarbon solvents". Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363228.
Texto completo da fonteAdams, Melissa Marie. "The anaerobic oxidation of short-chain alkanes in hydrothermal vents". Thesis, Harvard University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3626342.
Texto completo da fonteMicroorganisms are central to the cycling of methane on Earth. The anaerobic oxidation of methane (AOM) is a globally important process in anoxic marine sediments, which is often coupled to the reduction of sulfate by anaerobic methanotroph (ANME) archaea and sulfate reducing bacteria (SRB). However, the environmental and geochemical conditions that constrain these microbial communities remain largely uncharacterized. In this dissertation, I present evidence that methane and C2-C4 alkanes are substantial sources of metabolic energy in sedimented hydrothermal vent systems. Furthermore, these studies demonstrate that AOM and C2-C4 alkane oxidation linked to sulfate reduction (SR) are governed by temperature and substrate availability.
Using continuous-flow sediment bioreactors and batch incubations, rate measurements revealed a striking uncoupling of AOM from SR across the thermal gradient characteristic of hydrothermal vent sediments, with AOM occurring at the highest temperature (90°C) in the absence of SR. I discovered that ANMEs were present in sediments at all temperatures investigated, including a unique thermophilic ANME clade, while SRB were only detected in cooler regimes. Next, I present data from batch incubations demonstrating for the first time that substantial C2-C4 alkane oxidation occurs over a broad temperature range (25 - 75°C) in hydrothermal vent sediments and is coupled to SR up to 75°C with maximum rates at 55°C. Furthermore, there was preferential degradation of C2-C4 alkanes at 55°C, indicating that the active alkane oxidizers are thermophilic. At the rate maxima, 16S rRNA pyrotag sequence data revealed that a novel SRB lineage was the likely phylotype mediating the anaerobic oxidation of C 2-C4 alkanes.
Finally, I present a comparative study of methane- and sulfur-cycling ecotypes in geographically separated hydrothermal vent and hydrocarbon seep sediments. By employing high throughput sequencing of 16S rRNA genes coupled to geochemical data, I was able to establish the environmental constraints that determine ANME and SRB ecotype diversity and distribution in these biogeochemically distinct deep sea habitats. In summary, this dissertation sheds light on the pervasive effects of temperature, substrate availability, and habitat type on these metabolic processes that are critical for the cycling of carbon and sulfur in deep sea hydrothermal vent sediments.
Garba, Mustapha Danlami. "Valorisation of alkanes and alkynes by transhydrogenation in petrochemical processes". Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8719/.
Texto completo da fonteModak, Viraj Prakash. "Surface Freezing in n-Alkanes: Experimental and Molecular Dynamics Studies". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449013699.
Texto completo da fonteHan, Kyung-Eun. "Transport of n-alkanes through graphene nanoporous atomically thin membrane". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123294.
Texto completo da fonteCataloged from PDF version of thesis.
Includes bibliographical references (pages 67-68).
Accurately characterizing molecular transport through a nanoporous atomically thin graphene membrane is important in determining potential for graphene's application as a filter. Amongst many factors that affect the transport, the effect of size of molecules is analyzed in this paper. Diffusion of n-alkanes between C10 and C18 was analyzed to isolate the effect of molecule size in transport trends. The n-alkanes are chosen as the solutes for their similar long-chains but differing lengths. Differently branched structures cause variable interactions with graphene between molecules. Thus, this structural consistency in n-alkanes make them optimal solutes. Additionally, these molecules are comprised of only carbon and hydrogen, allowing the same functional groups and polarities. However, their distinct boiling points allow detection in the gas chromatography-mass spectrometry (GCMS).
A diffusion cell with feed and permeate chambers, separated by a semipermeable membrane, was used to induce diffusion with difference in solute concentration between the chambers. Diffusion concentration and rates were calculated using GCMS analysis of samples taken over 6-hour period during the diffusion. The calculations were done for diffusion with and without graphene membrane for comparison. When integrating the GCMS peaks, two types of integration methods - wide-peak and narrow-peak integrations - were used to estimate the error due to difficulties in identifying peak boundaries. These results were further compared to the inherent diffusivity coefficients of the molecules, in order to quantify the selectivity imparted by graphene for diffusion. The diffusion trends from each data set were compared to the diffusion trend from inherent diffusivity coefficients, which shows that diffusiyity should decrease with larger and heavier n-alkanes.
The experimentally obtained data shows that smaller molecules diffused at faster rates, and there was a noticeable drop in the diffusion transport between C 12 and C 14. This is consistent with the expected trend. Studies that minimize sources of errors are recommended to further understand the transport of alkanes through graphene.
by Kyung-Eun Han.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering